There are a number of conventional circuit designs for the detection, identification, and/or activation of digital devices that have unique digital registration numbers. One such digital device is an IButton® microprocessor (Dallas Semiconductor), which may contain a memory, a real-time clock, a transaction counter, a temperature sensor, and/or the like. The microprocessor is typically connected via a one-wire interface that is a serial data bus. In order to utilize, troubleshoot, and repair these circuit designs, the prior art discloses using a switching network to identify the location of a specific digital device.
What is still needed in the art, however, is a system that consists of discreet modular units that may be added or subtracted as needed, as well as a means for querying a circuit to detect, identify, and/or activate a specific module.
U.S. Pat. No. 6,693,538 (issued to Maloney on Feb. 17, 2004) discloses one specific application of the digital devices described above. Object carriers are provided for use with an object tracking and control system of a type having a storage receptacle with a tray provided with an array of slots for receiving identification (ID) tags bearing touch memory devices. A computer-based controller is provided for detecting the absence or presence and identity of ID tags disposed in the slots. The carrier includes a container with an openable panel for placing objects in and removing objects from the carrier. A thin plastic tongue projects from the carrier and bears a touch memory device. Carriers bearing objects to be tracked are placed in the storage receptacle with their tongues extending into the slots of the receptacle. The controller thus detects and logs the removal and replacement of the carrier in the storage receptacle. In one embodiment, the opening and closing of the carrier when it is not stored in the receptacle is detected and logged for tracking access to the carrier in more detail. In general, each of the carriers includes an internal addressable switch having one or more input/output (I/O) ports; an on-board sensor, such as a loop-detector sensor for detecting when an object is removed from the carrier, a reed switch for detecting the opening of the carrier, or another type of sensor depending on the intended use of the system; and a light-emitting diode (LED) attached to the carrier.
What is still needed in the art, however, is a system that is simpler, omitting the internal addressable switch and the one or more I/O ports, and associating the LEDs with the storage receptacle, as opposed to the carriers.